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  <div class="section" id="s-django-1-4-11-release-notes">
<span id="django-1-4-11-release-notes"></span><h1>Django 1.4.11 release notes<a class="headerlink" href="#django-1-4-11-release-notes" title="Permalink to this headline">¶</a></h1>
<p><em>April 21, 2014</em></p>
<p>Django 1.4.11 fixes three security issues in 1.4.10. Additionally,
Django&#8217;s vendored version of six, <a class="reference internal" href="../topics/python3.html#module-django.utils.six" title="django.utils.six"><tt class="xref py py-mod docutils literal"><span class="pre">django.utils.six</span></tt></a>, has been
upgraded to the latest release (1.6.1).</p>
<div class="section" id="s-unexpected-code-execution-using-reverse">
<span id="unexpected-code-execution-using-reverse"></span><h2>Unexpected code execution using <tt class="docutils literal"><span class="pre">reverse()</span></tt><a class="headerlink" href="#unexpected-code-execution-using-reverse" title="Permalink to this headline">¶</a></h2>
<p>Django&#8217;s URL handling is based on a mapping of regex patterns
(representing the URLs) to callable views, and Django&#8217;s own processing
consists of matching a requested URL against those patterns to
determine the appropriate view to invoke.</p>
<p>Django also provides a convenience function &#8211;
<a class="reference internal" href="../ref/urlresolvers.html#django.core.urlresolvers.reverse" title="django.core.urlresolvers.reverse"><tt class="xref py py-func docutils literal"><span class="pre">reverse()</span></tt></a> &#8211; which performs this process
in the opposite direction. The <tt class="docutils literal"><span class="pre">reverse()</span></tt> function takes
information about a view and returns a URL which would invoke that
view. Use of <tt class="docutils literal"><span class="pre">reverse()</span></tt> is encouraged for application developers,
as the output of <tt class="docutils literal"><span class="pre">reverse()</span></tt> is always based on the current URL
patterns, meaning developers do not need to change other code when
making changes to URLs.</p>
<p>One argument signature for <tt class="docutils literal"><span class="pre">reverse()</span></tt> is to pass a dotted Python
path to the desired view. In this situation, Django will import the
module indicated by that dotted path as part of generating the
resulting URL. If such a module has import-time side effects, those
side effects will occur.</p>
<p>Thus it is possible for an attacker to cause unexpected code
execution, given the following conditions:</p>
<ol class="arabic simple">
<li>One or more views are present which construct a URL based on user
input (commonly, a &#8220;next&#8221; parameter in a querystring indicating
where to redirect upon successful completion of an action).</li>
<li>One or more modules are known to an attacker to exist on the
server&#8217;s Python import path, which perform code execution with side
effects on importing.</li>
</ol>
<p>To remedy this, <tt class="docutils literal"><span class="pre">reverse()</span></tt> will now only accept and import dotted
paths based on the view-containing modules listed in the project&#8217;s <a class="reference internal" href="../topics/http/urls.html"><em>URL
pattern configuration</em></a>, so as to ensure that only modules
the developer intended to be imported in this fashion can or will be imported.</p>
</div>
<div class="section" id="s-caching-of-anonymous-pages-could-reveal-csrf-token">
<span id="caching-of-anonymous-pages-could-reveal-csrf-token"></span><h2>Caching of anonymous pages could reveal CSRF token<a class="headerlink" href="#caching-of-anonymous-pages-could-reveal-csrf-token" title="Permalink to this headline">¶</a></h2>
<p>Django includes both a <a class="reference internal" href="../topics/cache.html"><em>caching framework</em></a> and a system
for <a class="reference internal" href="../ref/contrib/csrf.html"><em>preventing cross-site request forgery (CSRF) attacks</em></a>. The CSRF-protection system is based on a random nonce
sent to the client in a cookie which must be sent by the client on future
requests and, in forms, a hidden value which must be submitted back with the
form.</p>
<p>The caching framework includes an option to cache responses to
anonymous (i.e., unauthenticated) clients.</p>
<p>When the first anonymous request to a given page is by a client which
did not have a CSRF cookie, the cache framework will also cache the
CSRF cookie and serve the same nonce to other anonymous clients who
do not have a CSRF cookie. This can allow an attacker to obtain a
valid CSRF cookie value and perform attacks which bypass the check for
the cookie.</p>
<p>To remedy this, the caching framework will no longer cache such
responses. The heuristic for this will be:</p>
<ol class="arabic simple">
<li>If the incoming request did not submit any cookies, and</li>
<li>If the response did send one or more cookies, and</li>
<li>If the <tt class="docutils literal"><span class="pre">Vary:</span> <span class="pre">Cookie</span></tt> header is set on the response, then the
response will not be cached.</li>
</ol>
</div>
<div class="section" id="s-mysql-typecasting">
<span id="mysql-typecasting"></span><h2>MySQL typecasting<a class="headerlink" href="#mysql-typecasting" title="Permalink to this headline">¶</a></h2>
<p>The MySQL database is known to &#8220;typecast&#8221; on certain queries; for
example, when querying a table which contains string values, but using
a query which filters based on an integer value, MySQL will first
silently coerce the strings to integers and return a result based on that.</p>
<p>If a query is performed without first converting values to the
appropriate type, this can produce unexpected results, similar to what
would occur if the query itself had been manipulated.</p>
<p>Django&#8217;s model field classes are aware of their own types and most
such classes perform explicit conversion of query arguments to the
correct database-level type before querying. However, three model
field classes did not correctly convert their arguments:</p>
<ul class="simple">
<li><a class="reference internal" href="../ref/models/fields.html#django.db.models.FilePathField" title="django.db.models.FilePathField"><tt class="xref py py-class docutils literal"><span class="pre">FilePathField</span></tt></a></li>
<li><a class="reference internal" href="../ref/models/fields.html#django.db.models.GenericIPAddressField" title="django.db.models.GenericIPAddressField"><tt class="xref py py-class docutils literal"><span class="pre">GenericIPAddressField</span></tt></a></li>
<li><a class="reference internal" href="../ref/models/fields.html#django.db.models.IPAddressField" title="django.db.models.IPAddressField"><tt class="xref py py-class docutils literal"><span class="pre">IPAddressField</span></tt></a></li>
</ul>
<p>These three fields have been updated to convert their arguments to the
correct types before querying.</p>
<p>Additionally, developers of custom model fields are now warned via
documentation to ensure their custom field classes will perform
appropriate type conversions, and users of the <a class="reference internal" href="../ref/models/querysets.html#django.db.models.query.QuerySet.raw" title="django.db.models.query.QuerySet.raw"><tt class="xref py py-meth docutils literal"><span class="pre">raw()</span></tt></a> and <a class="reference internal" href="../ref/models/querysets.html#django.db.models.query.QuerySet.extra" title="django.db.models.query.QuerySet.extra"><tt class="xref py py-meth docutils literal"><span class="pre">extra()</span></tt></a> query methods &#8211; which allow the
developer to supply raw SQL or SQL fragments &#8211; will be advised to ensure they
perform appropriate manual type conversions prior to executing queries.</p>
</div>
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  <h3><a href="../contents.html">Table Of Contents</a></h3>
  <ul>
<li><a class="reference internal" href="#">Django 1.4.11 release notes</a><ul>
<li><a class="reference internal" href="#unexpected-code-execution-using-reverse">Unexpected code execution using <tt class="docutils literal"><span class="pre">reverse()</span></tt></a></li>
<li><a class="reference internal" href="#caching-of-anonymous-pages-could-reveal-csrf-token">Caching of anonymous pages could reveal CSRF token</a></li>
<li><a class="reference internal" href="#mysql-typecasting">MySQL typecasting</a></li>
</ul>
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